This invention relates to a print coil wafer for converting mechanical vibrations into an electrical signal or vice versa.
In a conventional moving coil (MC) type pick-up cartridge, a coil is fixed to one end of a cantilever member and a stylus is secured to the other end thereof. As a result the mechanical vibrations picked up by the stylus are converted into an electrical signal. Generally, since the coils for the MC type cartridges are wound coils, the mass of the coils is relatively large, thereby exerting a bending force on the cantilever member. In addition, the magnetic circuit becomes relatively large. Furthermore, such wound coils are not preferable in terms of mass production, since highly refined techniques are required for accurately winding the coils.
In order to overcome the above drawbacks, a print coil wafer has been proposed, in which a coil, in the form of an electrically conductive coating, is formed or printed on an insulating wafer. However, since the insulating wafer is made of a resin, such as polyamide, in the form of a very thin sheet, the heat-resisting property thereof is poor. As a result, the insulating wafer tends to be creased when the electrically conductive material is coated thereon. Furthermore, since the insulating wafer absorbs ultrasonic vibrations, an ultrasonic bonder cannot be utilized to connect lead lines to the coil on the wafer. Finally, the property of the insulating wafer tends to be deteriorated by its resonance or deformation.